[llvm] 0bf75d8 - Handle the unexpected inputs for pass HardwareLoops

[via llvm-commits]

Author: Wang, Xin10
Date: 2023-03-30T10:42:19+08:00
New Revision: 0bf75d85419e87d3cb0352f7ebc8ef252869e9f6

URL: https://github.com/llvm/llvm-project/commit/0bf75d85419e87d3cb0352f7ebc8ef252869e9f6
DIFF: https://github.com/llvm/llvm-project/commit/0bf75d85419e87d3cb0352f7ebc8ef252869e9f6.diff

LOG: Handle the unexpected inputs for pass HardwareLoops

For a function TryConvertLoop in pass HardwareLoops, wrong input arguments will
lead to crash. There will be 3 cases.
In line 342, compiler want to get something from
HWLoopInfo.CountType, which depends on if argument Bitwidth is given, if not,
will crash.
In Function isHardwareLoopCandidate, it dereference CountType too.
In Function InsertLoopDec, it dereference LoopDecrement.
They all could lead to crash. This patch add condition to this pass, when we meet unexpected inputs then skip
the pass.

Reviewed By: samparker, fhahn

Differential Revision: https://reviews.llvm.org/D146277

Added: 
    llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll

Modified: 
    llvm/include/llvm/Analysis/TargetTransformInfo.h
    llvm/lib/Analysis/TargetTransformInfo.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/TargetTransformInfo.h b/llvm/include/llvm/Analysis/TargetTransformInfo.h
index 3ce5f5c3f464b..c3e50addc7c6b 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -95,7 +95,7 @@ struct MemIntrinsicInfo {
 /// Attributes of a target dependent hardware loop.
 struct HardwareLoopInfo {
   HardwareLoopInfo() = delete;
-  HardwareLoopInfo(Loop *L) : L(L) {}
+  HardwareLoopInfo(Loop *L);
   Loop *L = nullptr;
   BasicBlock *ExitBlock = nullptr;
   BranchInst *ExitBranch = nullptr;

diff  --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index b536577640712..cdeffcbd8c5c1 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -108,6 +108,14 @@ IntrinsicCostAttributes::IntrinsicCostAttributes(Intrinsic::ID Id, Type *RTy,
   Arguments.insert(Arguments.begin(), Args.begin(), Args.end());
 }
 
+HardwareLoopInfo::HardwareLoopInfo(Loop *L) : L(L) {
+  // Match default options:
+  // - hardware-loop-counter-bitwidth = 32
+  // - hardware-loop-decrement = 1
+  CountType = Type::getInt32Ty(L->getHeader()->getContext());
+  LoopDecrement = ConstantInt::get(CountType, 1);
+}
+
 bool HardwareLoopInfo::isHardwareLoopCandidate(ScalarEvolution &SE,
                                                LoopInfo &LI, DominatorTree &DT,
                                                bool ForceNestedLoop,

diff  --git a/llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll b/llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll
new file mode 100644
index 0000000000000..86d0213e84de4
--- /dev/null
+++ b/llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll
@@ -0,0 +1,37 @@
+; RUN: opt -passes='hardware-loops<force-hardware-loops>' -S %s -o - | FileCheck %s --check-prefix=CHECK
+; RUN: opt -passes='hardware-loops<force-hardware-loops;hardware-loop-decrement=1>' -S %s -o - | FileCheck %s --check-prefix=CHECK
+; RUN: opt -passes='hardware-loops<force-hardware-loops;hardware-loop-counter-bitwidth=32>' -S %s -o - | FileCheck %s --check-prefix=CHECK
+
+define void @while_lt(i32 %i, i32 %N, ptr nocapture %A) {
+; CHECK-LABEL: @while_lt(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP4:%.*]] = icmp ult i32 [[I:%.*]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP4]], label [[WHILE_BODY_PREHEADER:%.*]], label [[WHILE_END:%.*]]
+; CHECK:       while.body.preheader:
+; CHECK-NEXT:    [[TMP0:%.*]] = sub i32 [[N]], [[I]]
+; CHECK-NEXT:    call void @llvm.set.loop.iterations.i32(i32 [[TMP0]])
+; CHECK-NEXT:    br label [[WHILE_BODY:%.*]]
+; CHECK:       while.body:
+; CHECK-NEXT:    [[I_ADDR_05:%.*]] = phi i32 [ [[INC:%.*]], [[WHILE_BODY]] ], [ [[I]], [[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[A:%.*]], i32 [[I_ADDR_05]]
+; CHECK-NEXT:    store i32 [[I_ADDR_05]], ptr [[ARRAYIDX]], align 4
+; CHECK-NEXT:    [[INC]] = add nuw i32 [[I_ADDR_05]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = call i1 @llvm.loop.decrement.i32(i32 1)
+; CHECK-NEXT:    br i1 [[TMP1]], label [[WHILE_BODY]], label [[WHILE_END]]
+; CHECK:       while.end:
+; CHECK-NEXT:    ret void
+entry:
+  %cmp4 = icmp ult i32 %i, %N
+  br i1 %cmp4, label %while.body, label %while.end
+
+while.body:
+  %i.addr.05 = phi i32 [ %inc, %while.body ], [ %i, %entry ]
+  %arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.addr.05
+  store i32 %i.addr.05, ptr %arrayidx, align 4
+  %inc = add nuw i32 %i.addr.05, 1
+  %exitcond = icmp eq i32 %inc, %N
+  br i1 %exitcond, label %while.end, label %while.body
+
+while.end:
+  ret void
+}